Method of manufacturing zinc oxid.



L. S. HUGHES.

METHOD OF MANUFACTURING ZINC OXID.

APPLICATION FILED NOV. 13, 1906. RENEWED NOV.27,1908.

' Patented May 4, 1909.v

WITNESSES A TTORNEY.

. NITE STATES PATENT OFFICE.

LOUIS S. HUGHES, OF .IOPLIN, MISSOURI, ASSIGNOR TO IICHER LEAD COMPANY, OF JOPLIN,

' MISSOURI, A CORPORATION OF MISSOURI.

METHOD OF MANUFACTURING ZINC OXID.

Specification of Letters Patent.

Patented May 4, 1909.

Application filed November 13, 1906, Serial No. 343,283. Renewed November 27, 1908. Serial No. 464,784.

ods of Manufacturing Zinc Oxid, of which, the following is a true and exact description,

reference being bad to the accom anying drawings, which form a part thereo My invention relates to the manufacture of 'zinc oxid from zinc sulfid and has for its object to provide for an economical and efficient manufacture of the zinc oxid from sulfid ores and in desirable commercial condition.

My improved method consists in finely dividing theizinc sulfid ore or. compound, heating a furnace by gas flames to a temperature at which the zmc sulfid in admixture with air will be decomposed and zinc oxid formed; feeding the air to the heated portion of the furnace by means of an air jet; separating the zinc oxid and furnace gases from heavy impurities by. subsidence and finally separating the zinc oxid from the gases by screening. The decomposition of the ore and the formation of the zinc oxid will take place at a temperature of approximately 1100 F. and it is a matter of importance that the temperature of the furnace should not be permitted to exceed 1600 F. because in excess of this temperature any iron oxid which may contaminate the zinc oxid will have greater brilliance with increased discoloring effect and because also in excess of this temperature cadmium, which is generally pres ent in zinc ores, will be burned to an oxid which will'discolor the zinc oxid being inseparable therefrom. It is also highly important, in case any lead is present in admixture with the zmc that the temperature ofthe walls of the furnace should be maintained below the point at which the lead product formed would adhere to them. For the best results I practice my process in a vertical unlined furnace of thin sheet metal the walls of which are maintained at a temerature not materially in excess of 1200" F. by conduction and the escape of heat from the outer walls by radiatlon and contact with atmospheric air.

In my copending application for Letters Patent Serial Number 300,966, filed Febr'ua-ry 12th, 1906, I have described a very similar treatment of lead sulfid ores for the production of the pigment known as sublimed white lead and largely consisting of lead sulfate.

My present application has especially in view the treatment of zinc ores, though of course it will be understood that in either application. the presence of a mixed ore would involve the conjoint practice of both processes.

The apparatus which I have found it best to use in practicing my invention has the features of construction which are described and claimed in my copending applications for Letters Patent, one filed March 20, 1906 Serial Number 306,954 and the other filed October 22, 1906 Serial Number 339,804, such an apparatus being shown in the drawings forming part of this application and in which Figure 1 is a side elevation of the furnace with fine and screen system attached thereto, the furnace being partly shown in central verticalsection, and Fig. 2 is a cross-section on the line 22 of Fig. '1.

A indicates the cylindrical walls of the furnace formed of thin unlined sheet metal, and )rovided with a hopper shaped bottom A 0 the same material having one or more openings indicated at A for the admission of air and the outlet of unburned particles which settle in the furnace; A indicating the normally closed opening by which access is had to the interior of the furnace.

B is an air jet pipe directed axially upward from the bottom of the furnace and supplied by an air pipe B.

O is a flue leading from the top of the furnace provided with settling chambers C Q and connecting as shown, to a draft fan D, with the fiues C C the latter flue having hoppers C C opening into its bottom for the reception of the zinc oxid and connecting at top with screen bags indicated at E, E, through which the furnace gases escape.

F indicates a gas pipe supplying an annular gas ring F havlng pro ecting from is a hopper in which the finely divided 11c ore is placed and which communicates with the interior of the furnace through a bhute H having a trough like end H which projects to or nearly to the center. of the furnace so as to deliver the ore directly into the upwardly moving air jet from the jet pipe.

I is a gate for regulating the feed and J a rapping or vibrating device acting on the hopper and chute so as to keep the metal of which they are made in vibration and insure a constant and even feed of ore.

In practice the gas and air admitted through the burners G is ignited, forming a central flame, indicated at K, surrounded in its lower parts by an air jacket indicated at L and derived from the air entering the bottom of the furnace at -A The zinc sulfid ore in a fine state of division is fed from the hopper H through the chute H and trough H to the center of the issuing air jet from the pipe B which projects it in a fine state of division and separation into the heat zone of the furnace where a very prompt decomposition of the ore takes place with the formation of zinc oxid, the heavier impurities settle in the vertical furnace and finally escape through the opening A while the zinc oxid in admixture with the furnace gases passes into the flue G, the heavier impurities settling in the flue C, and the oxid being separated from the furnace gases in the screen system E and caught in thehoppers C 1 Having now described my invention, what Iclaim as new and desire to secure by Letters Patent is j 1. The method of manufacturing zinc oxid from zinc sulfid which consists in finely dividing the zinc sulfid ore or compound, heating a furnace by an internal gas flame to a temperature at which the zinc sulfid in admixture with air will be decomposed and zinc oxid formed, feeding the ore to the heated portion of the furnace by means of an air jet, separating the zinc oxid and fur" nace gases from impurities by subsidence and separating the zincoxid from the gases by screening.

2. The method of manufacturing zinc oxid from zinc sulfid which consists in finely dividing the zinc sulfid ore or compound, heating a furnace by an internal gas flame to a temperature at which the zinc sulfid in admixture with air will be decomposed and zinc oxid formed while conducting away the heat of the furnace to maintain its temperature at a point below that at which the zinc oxid is injured or contaminated, feeding the ore to the heated portion of the furnace by means of an air jet, separating the zinc oxid and furnace gases from impurities by subsidence and separating the zinc oxid from the gases by screening.

3. The method of manufacturing zinc oxid from zinc sulfid which consists in finely dividing the zinc sulfid ore or compound, heating a vertical furnace by internal nonreducing gas flames to a temperature at which the zinc sulfid is decomposed and zinc oxid formed while driving off heat from the furnace by conduction to maintain its temperature below the point where the zinc oxid is injured, feeding the ore to the heated portion of the furnace by an air jet directed upward from the bottom of the furnace, separating the zinc oxid from undecomposed ore and heavier impurities by subsidence in the furnace, drawing off the furnace gases and zinc, oxid from the top of the furnace and separating the oxid by screening. y

-LOUIS S. HUGHES. lVitnesses BELLE SPARKS, 9

June CHARLOW. 

